2022-11-29 12:56:29

by Peter Newman

Subject: [PATCH v2 1/2] x86/resctrl: Factor rdtgroup lock for multi-file ops

rdtgroup_kn_lock_live() can only release a kernfs lock for a single file
before waiting on the rdtgroup_mutex, limiting its usefulness for
operations on multiple files, such as rename.

Factor the work needed to respectively break and unbreak active
protection on an individual file into rdtgroup_kn_{get,put}().

This refactoring should not result in any functional change.

Signed-off-by: Peter Newman <[email protected]>
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 35 ++++++++++++++++----------
1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index e5a48f05e787..03b51543c26d 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2026,6 +2026,26 @@ static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn)
}
}

+static void rdtgroup_kn_get(struct rdtgroup *rdtgrp, struct kernfs_node *kn)
+{
+ atomic_inc(&rdtgrp->waitcount);
+ kernfs_break_active_protection(kn);
+}
+
+static void rdtgroup_kn_put(struct rdtgroup *rdtgrp, struct kernfs_node *kn)
+{
+ if (atomic_dec_and_test(&rdtgrp->waitcount) &&
+ (rdtgrp->flags & RDT_DELETED)) {
+ if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
+ rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
+ rdtgroup_pseudo_lock_remove(rdtgrp);
+ kernfs_unbreak_active_protection(kn);
+ rdtgroup_remove(rdtgrp);
+ } else {
+ kernfs_unbreak_active_protection(kn);
+ }
+}
+
struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
{
struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn);
@@ -2033,8 +2053,7 @@ struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
if (!rdtgrp)
return NULL;

- atomic_inc(&rdtgrp->waitcount);
- kernfs_break_active_protection(kn);
+ rdtgroup_kn_get(rdtgrp, kn);

mutex_lock(&rdtgroup_mutex);

@@ -2053,17 +2072,7 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn)
return;

mutex_unlock(&rdtgroup_mutex);
-
- if (atomic_dec_and_test(&rdtgrp->waitcount) &&
- (rdtgrp->flags & RDT_DELETED)) {
- if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP ||
- rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED)
- rdtgroup_pseudo_lock_remove(rdtgrp);
- kernfs_unbreak_active_protection(kn);
- rdtgroup_remove(rdtgrp);
- } else {
- kernfs_unbreak_active_protection(kn);
- }
+ rdtgroup_kn_put(rdtgrp, kn);
}

static int mkdir_mondata_all(struct kernfs_node *parent_kn,
--
2.38.1.584.g0f3c55d4c2-goog